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VLAN Configuration for servers on different IP range

Rajat.Kothari
Level 1
Level 1

 

Hello everyone ,

 

At our company we  have having two different IP range(10.101.36.0/23), and in both IP we have different imporatnt servers.

 

My question is that we need to create VLAN by Cisco 3750x in our office, can it be possible without disturbing the servers IP's.

What is the best solution in our scenario, we want VLAN for servers, data and voice.

what is the solution??

12 Replies 12

Hi, the impact is 0 when add new Vlan on the switch, and when the switch is spaneeng  tree root  in that network 

I could not understand your reply.

 

We are not facing in creating VLAn , but facing problem because of servers on different Ip rangesay ne server is on 10.101.37.37 and another on 10.101.36.50, and like this.

How the VLAN can be configure in this scenario.??

 

 

Hi Nagendra we have two subnets as follows:-

1. 10.101.36.0- 36.255

2. 10.101.37.0- 37.255

 

 and yes we are having servers on both IP range.

 

With this VLAN is to be created, we want to know whether is there any solution or we need to change the IP's of servers so that they can come in one subnet (say 10.101.36.0/23) for all servrs.

Hi Rajatk, if i understand correctly you need to delete the second Vlan   (10.101.37.0- 37.255) and to increase the first one. For this you need to change the defaul gateway for all servers that are in the second vlan to first vlan 

Example:

interface vlan 10 
 ip address 10.101.36.1 255.255.255.0
!
interface vlan 20 
 ip address 10.101.37.1 255.255.255.0
 
no interface vlan 20
interface vlan 10
ip address 10.101.36.1 255.255.254.0 

 

And put all servers in vlan 10 

we do not have VLAN for our office, but we want to create it.

We have purchased the cisco catalyst 3750 x for VLAN, but could not get due to servers on differnt IP subnet.

 

Note:- we do not have any VLAn exist for now.

interface vlan 10
ip address 10.101.36.1 255.255.254.0 

 

And configure ta port to the server 

 

interface g1/0/x

switchport mode access

switchport access vlan 10

spanning-tree portfast

 

Constantin

If i understood, this is the solution :

10.101.36.0 / 24   VLAN 10
10.101.37.0 / 24   VLAN 20

This is the configuration :

interface vlan 10
  ip address 10.101.36.1 255.255.255.0
interface vlan 20
  ip address 10.101.37.1 255.255.255.0
interface FastEthernet0/1
 switchport access vlan 10
interface FastEthernet0/2
 switchport access vlan 20

On the server One
 ip      192.168.36.10
 netmask 255.255.255.0
 gateway 192.168.36.1

 

On the server Two
 ip      192.168.37.10
 netmask 255.255.255.0
 gateway 192.168.37.1
 

 

hey walter ,

 

Whether Vlan 10 would be accessible to vlan 20 and also how my users on data side will access dieeferent vlan

If you enable ip routing on the switch then it will forward traffic between vlans/subnets and then vlan 10 is accessible from vlan 20. Users on data side will access different vlans if they their default gateway configured to be the IP address of the switch vlan interface for their vlan.

 

HTH

 

Rick

HTH

Rick

It is a somewhat common misunderstanding to believe that you have no vlans if you have not configured vlans. But that is not correct. If you are connecting your PCs and servers to a switch then you have a vlan. The switch ports are automatically members of a vlan and the default vlan is 1. So currently all of your devices are in vlan 1.

 

You can, if you want to, configure a second vlan and assign some of the switch ports to that vlan.

 

Another point that might help is that while we tend to think that there is a one to one relationship between vlan and subnet (a vlan has a single subnet and a subnet has a single vlan) that is not necessarily the case. What you have described so far is that you have a single vlan and it has two subnets active in the same vlan. There are reasons why it is usually best to have the one to one relationship between vlan and subnet. But that is not a requirement and that is not what you currently have.

 

HTH

 

Rick

HTH

Rick

Nagendra Kumar Nainar
Cisco Employee
Cisco Employee

Hi Rajat,

 

Not sure, I understood the question. Did you mean, you have 2 subnets (10.101.36.0/23 and something else) and have servers in both the subnet?. Or you want to subnet 10.101.36.0/23 into 2 subnets?.

-Nagendra

sheastma
Cisco Employee
Cisco Employee

Hey Rajat.Kothari,

I believe I understand your question and I would like to help.

So, if I understand correctly you want to have two different vlans and keep the servers IP the same but have them accessible only to certain users. 

I believe the solution for this would be Private VLANs.

With this solution you can put everything in your network in the same vlan (the primary VLAN /23) and then use different subdomains to split up your network as you need.

Here is a link on how to configure Private VLAN's

http://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus5000/sw/configuration/guide/cli/CLIConfigurationGuide/PrivateVLANs.html

 

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